.global fork
fork:
    li a7, 1
    ecall
    ret

.global exit
exit:
    li a7, 2
    ecall
    ret

.global wait
wait:
    li a7, 3
    ecall
    ret

.global kill
kill:
    li a7, 4
    ecall
    ret

.global getpid
getpid:
    li a7, 5
    ecall
    ret

.global write
write:
    li a7, 6
    ecall
    ret

.global read
read:
    li a7, 7
    ecall
    ret

.global sbrk
sbrk:
    li a7, 8
    ecall
    ret